1. Field of the Invention
The present invention relates to a system for controlling an air-conditioning system within an environment, in particular the passenger compartment of a vehicle.
As is known, the sensation of thermal comfort perceived by the occupants of an air-conditioned environment does not depend only upon the temperature of the air introduced into the environment by the air-conditioning system, but upon all the factors that affect heat exchange between the occupants and the environment.
Various studies, conducted with the purpose of detecting the sensation of thermal comfort perceived by the occupants of a vehicle equipped with an air-conditioning system of a traditional type, have shown how the temperature value used by the air conditioner for regulating the temperature of the air introduced into the passenger compartment is frequently not correlated to the thermal sensation perceived by the passengers of the vehicle, and how automatic regulation of the air-conditioning system is frequently unable to create the conditions necessary for giving the occupants of the vehicle an optimal sensation of thermal comfort.
In particular, as regards vehicles with passenger compartments of large dimensions, for example buses, it has been shown experimentally how the sensation of thermal comfort perceived by the occupants of said vehicles may vary considerably from occupant to occupant according to their position inside the passenger compartment.
The main cause of these differences, as mentioned above, is to be sought mainly in the thermal exchanges that occur between the passengers and their environment.
In a bus, for example, in which the top part of the side walls is frequently formed by transparent surfaces made of glass, it is clear how, in the case where these are directly exposed to rays of sunlight, they will have a temperature considerably higher than that of the air of the passenger compartment and markedly condition the thermal sensation of the passengers.
To improve the sensation of thermal comfort perceived by the passengers of a vehicle equipped with an air-conditioning system, systems for controlling air-conditioning systems have been developed, which take into account also the thermal exchanges that occur between the passengers and their environment.
2. Description of Related Art
Described in the patent FR-2.821.659, for example, is a system for controlling an air-conditioning system, comprising a processing and control unit (ECU) provided for driving actuator devices for actuating the air-conditioning system according to pre-set modalities, as a function of signals supplied by sensors and by a device for setting the desired temperature. Said unit comprises processing means provided for estimating the instantaneous value of an equivalent temperature according to a pre-set function that depends only upon the temperature of the treated air, upon the mean radiant temperature detected in a portion of the air-conditioned environment, and upon the flow rate of the treated air introduced into said environment.